Actual Ah demand for AirCon

[CaptainRivet]

Originally Posted by ekelly36

Question.... as I am also planning to add AC because well.... the wife wants it.... for this really I was just thinking about either installing a overhead RV AC aircon or attempting to place a AC minisplit system, both will come with challenges but from all the reading I have done I have a couple options..... 4k inverter with 1200Ah lifepo4 and a small gen to make up the difference for the 1200w solar or smaller everything else and a little bigger generator, seeming as I will need to carry gas in cans for the dinghy either way is ok with me.... of course I could be missing something but the RV units and minisplits advertise 10-20Ah usage if memory serves..... on a 1200 Ah bank 20 amps an hour for the AC is not a deal breaker for me.... I admit actual use and just research are completely different things so I guess we will see...... The MAIN issue is.... the wife lol.... she has to be comfortable or well.... it wont be fun lol

AC on a 33ft boat, take the 12V Marbu or the base unit i posted in the 12k btu i posted above and job done.
no big inverters and depending on it. in 12V there is no 4k inverter with the surge capapilities you need means 2xMulti 2000 in parallel, well i would right away take the 3000 but do you have space for either???
you can start discussing AC or DC for boats >44ft or cats where you have space for the large AC installation you need. you also have to add inverter losses, 2 inverters in parallel standby is 50W continious minimum.
but on small boats where space is super premium, no space for enough solar the DC route is the way to go. then take a wakespeed regulator and put as large as possible alternator on your engine so everytime you motor you shuffle in max energy you can. wakespeed because that alternator will steel you a lot hp from your small engine, you wanna automatically dial back its output in relation to RPM of engine and for bad condition or manuveruing in tide habours you wanna dial the alternator back or adapt the output to match the condition you have to motor in. here the wakespeed is absolutly worth every penny and the way to go.
you may need the little honda gen but you won't use it much less like this. plus again that relies again on your shorepower charger...much better largest alternator on engine with the wakespeed with 12V aircon.

[s/v Jedi]

Or you just research product offerings better and save some money.

https://www.imarineusa.com/www.imari...ir24832JU.aspx

[OneBoatman]

10,000 BTU of AC wouldn't be enough in conditions of high RH. You will need at least 16,000 BTU just to be comfortable when the humidity gets up near 100%. Much depends on how well the boat is insulated and how you ventilate it. You should design it around a 50% duty cycle. The problem we face is how to replace what we use allowing for refrigeration/freezing, lighting, and start reserve. If you use an inverter for any AC devices you of course need more capacity. Having 600 ah vs 400ah available only means that you can draw them down 50% longer so, what matters is how fast can you replace what you use. Some combination of wind and solar along with moderate battery capacity and reasonable alternator capacity is where most people end up. My brother-in-law settled on 600ah capacity on his Jeanneau 46 being equipped but has both wind generator plus 400 watts of solar. He can run both his AC units when needed without worries. Yet a friend that is a summer liveaboard in CT on 38 ft C&C now with 400 ah of Lithium batteries found he needs to add to his current 600 watts of solar to keep from having to run his generator and that is without air conditioning simply because there wasn't as much sun last year as he expected. Space is precious.

[FlyingScot]

Pipe dream. The only way to have AC from solar is to MAXIMIZE solar and MAXIMIZE efficiency.

We have 2895Wp of solar and live in the Caribbean so generally sunny. We also have very efficient wiring (read large) and 12K 12V Mabrus. Still can't run them everyday all day. We definitely love having them and use them when we clean the inside of the boat. It helps A LOT!

Everyone seems to think that replacing the energy is easy. It's not. The larger your house bank the harder it is to fill it back up. Ours is 1320Ah (12v).

We are currently in San Blas Panama. Our daily harvests have been as low as 7kWh and as much as 17kWh in the last 3 weeks. We have little control over the clouds.

We have lots of other uses for power, so air conditioning is a trade off.

[CaptainRivet]

Originally Posted by FlyingScot

Pipe dream. The only way to have AC from solar is to MAXIMIZE solar and MAXIMIZE efficiency.

We have 2895Wp of solar and live in the Caribbean so generally sunny. We also have very efficient wiring (read large) and 12K 12V Mabrus. Still can't run them everyday all day. We definitely love having them and use them when we clean the inside of the boat. It helps A LOT!

Everyone seems to think that replacing the energy is easy. It's not. The larger your house bank the harder it is to fill it back up. Ours is 1320Ah (12v).

We are currently in San Blas Panama. Our daily harvests have been as low as 7kWh and as much as 17kWh in the last 3 weeks. We have little control over the clouds.

We have lots of other uses for power, so air conditioning is a trade off.

Fully agree with that.
And on a small boat with limited space for solar the only you can do, big LI bank and as big as alternator as possible. Anytime you run the engine you harvest whats there, solar keeps up with the normal loads.

[s/v Jedi]

Originally Posted by FlyingScot

Pipe dream. The only way to have AC from solar is to MAXIMIZE solar and MAXIMIZE efficiency.

We have 2895Wp of solar and live in the Caribbean so generally sunny. We also have very efficient wiring (read large) and 12K 12V Mabrus. Still can't run them everyday all day. We definitely love having them and use them when we clean the inside of the boat. It helps A LOT!

Everyone seems to think that replacing the energy is easy. It's not. The larger your house bank the harder it is to fill it back up. Ours is 1320Ah (12v).

We are currently in San Blas Panama. Our daily harvests have been as low as 7kWh and as much as 17kWh in the last 3 weeks. We have little control over the clouds.

We have lots of other uses for power, so air conditioning is a trade off.

A catamaran is difficult to cool down because of all the glazing and surface area hit by the sun. Awnings to shade the topsides helps enormously and when you have good ventilation and dry weather, one can do without A/C for most of the day.

Another point is that during the night you only need A/C in your cabin and with the sun down, it’s a much better picture to use A/C for that.

I fully agree with the energy production required to charge large batteries. It is easily dismissed by most who don’t have the large batteries yet while everyone with the large batteries will try to explain it. The batteries must be matched to the energy production capacity aboard; it isn’t to complement it.

[sailingharry]

Originally Posted by ekelly36

RV units and minisplits advertise 10-20Ah usage if memory serves..... on a 1200 Ah bank 20 amps an hour for the AC is not a deal breaker for me.

Several confusions in your post.

* First, I don't understand your units. You say it uses 10 to 20 Ah. Ah requires both current and time. Over. What period of time do they consume 10-20Ah?
* Amps an hour is not a meaningful collection of words.

" If you mean it consumes 10 to 20 amps at 12v, that seems exceptionally low. Conversely, if that is at 110v, that would be exceptionally high. I would expect more like 5A at 110V AC and 50A at 12V DC.

* You mention a mini split. Is that something available in the Marine market? Most mini split systems are household and require an air exchange. I'm not sure how you would set up the outside unit on a boat.

[SV Confianza]

Originally Posted by ekelly36

Question.... as I am also planning to add AC because well.... the wife wants it.... for this really I was just thinking about either installing a overhead RV AC aircon or attempting to place a AC minisplit system, both will come with challenges but from all the reading I have done I have a couple options..... 4k inverter with 1200Ah lifepo4 and a small gen to make up the difference for the 1200w solar or smaller everything else and a little bigger generator, seeming as I will need to carry gas in cans for the dinghy either way is ok with me.... of course I could be missing something but the RV units and minisplits advertise 10-20Ah usage if memory serves..... on a 1200 Ah bank 20 amps an hour for the AC is not a deal breaker for me.... I admit actual use and just research are completely different things so I guess we will see...... The MAIN issue is.... the wife lol.... she has to be comfortable or well.... it wont be fun lol

Make sure that you are not mixing up amps at 12v and amps at 120 (or 240)v. remember that Watts = Volts x Amps. So an AirCon that uses 20amps at 120v is 2400 Watts. At 12v from your batteries (not accounting for inverter losses), that is 200amps.

[SV Confianza]

Originally Posted by s/v Jedi

A catamaran is difficult to cool down because of all the glazing and surface area hit by the sun. Awnings to shade the topsides helps enormously and when you have good ventilation and dry weather, one can do without A/C for most of the day.
.

This point is not talked about enough. We finally got a sun shade for the foredeck 6 months ago. While it’s a pain in the neck to put up at times, the boat is maybe 10 degrees cooler with it up. It takes a LOT of energy to make up that 10 degrees.

The sunshade was an order of magnitude cheaper than all of our equipment to run our A/C from batteries.

Not talked about enough in these threads. Thanks for bringing it up.

[Baronkrak]

Originally Posted by sailingharry

Several confusions in your post. .

Really

Originally Posted by sailingharry

,,,,,Ah requires both current and time. .

Power and time

Originally Posted by sailingharry

What period of time do they consume 10-20Ah? .

Originally Posted by ekelly36

…20 amps an hour...

Originally Posted by SV Confianza

Watts = Volts x Amps.

Watts = Volts x Amps x pf.

Originally Posted by SV Confianza

So an AirCon that uses 20amps at 120v is 2400 Watts.

Not really.

[s/v Jedi]

Originally Posted by Baronkrak

Power and time

No, Ah is current and time. You really need to get these basic things right.

A stands for Amperes which is the current. It is a capital A because it was invented by Andre Empère. h stands for hours, which is time.

[RaymondR]

Originally Posted by s/v Jedi

A catamaran is difficult to cool down because of all the glazing and surface area hit by the sun. Awnings to shade the topsides helps enormously and when you have good ventilation and dry weather, one can do without A/C for most of the day.

Another point is that during the night you only need A/C in your cabin and with the sun down, it’s a much better picture to use A/C for that.

I fully agree with the energy production required to charge large batteries. It is easily dismissed by most who don’t have the large batteries yet while everyone with the large batteries will try to explain it. The batteries must be matched to the energy production capacity aboard; it isn’t to complement it.

It can get a bit warm in parts of Australia during the summer but I have found that with deck shading and a couple of 12 volt auto radiator fans wired in series in two of the deck hatches it can be comfortable for the hottest part of the day and I usually have to turn them off by about ten pm and rely just on the small cabin fans. The only down side is that the fans can be a bit noisy.

I am working on a gas engine driven aircon for the six or seven summer days when the heat is extreme.

[Baronkrak]

Originally Posted by s/v Jedi

No, Ah is current and time. You really need to get these basic things right.

A stands for Amperes which is the current. It is a capital A because it was invented by Andre Empère. h stands for hours, which is time.

May be in Hollywood.

https://en.wikipedia.org/wiki/Andr%C...ie_Amp%C3%A8re

[sailingharry]

Originally Posted by Baronkrak

May be in Hollywood.

https://en.wikipedia.org/wiki/Andr%C...ie_Amp%C3%A8re

Do you have meaningful contributions to make? If so, complete sentences, or at least complete thoughts, would be helpful. Your post a few above, with several quotes and a few words, was almost impossible to understand. This one as well.


Are you saying that the unit of Ampere isn't named after him? Or that he had no involvement in the advancement of the understanding of electrical theory? Or that Ah isn't Amperes X Time? Or that Ampere's aren't by convention capitalized?


My father tells a story about his lawyer, who on a fight with City Hall said "the best laywers can write a 2 sentence letter that requires the opposition to write (and pay for) a 3 page response." Likewise, you put near nothing on your post, and we rise to your bait with lengthy responses. Argh!



Truly, I can't tell if you agree with or disagree with the posts that are quoted. Since I and Jedi and SV Confianza have stated well established, non-controversial, fact based (not preferences or opinions) content, I can only assume (or hope!) that you are in an odd fashion agreeing with us.

[Putt-Putt]

Originally Posted by s/v Jedi

No, Ah is current and time. You really need to get these basic things right.

A stands for Amperes which is the current. It is a capital A because it was invented by Andre Empère. h stands for hours, which is time.

Perhaps it was just a typo, but Andre-Marie Ampere's name does indeed start with an A.

https://www.nist.gov/si-redefinition/ampere-history